Hox gene - These genes determine how a particular section of a developing embryo will develop. The amazing fact is the high degree of homology between these genes between different organisms. In fact, one can replace the gene for wing development from a fruit fly with the same gene from a chicken and the fly develops normally! It doesn't grow chicken wings!
Fireflies! New Work Shines Light on Hox Genes Responsible for Firefly Lantern Development - NeuroscienceNews.com Notion that Hox genes acquire new roles quickly, without compromising old ones, is novel. A firefly’s photic organ is functional throughout pupation and glows when the pupa is disturbed. Credit Armin Moczek and Matthew Stansbury.